Of course not, and I understand implementing an attacking style of play will take time (which is why I don't think he should have abandoned trying). However, from a fan's perspective, the more money you see invested in your team, particularly in attacking areas, you will want to see better quality attacking football. It remains to be seen whether Simeone is capable of gradually transitioning to that, but the evidence thus far is not promising.
I can't see Atletico falling out of the Champions League spots anytime soon, so they will continue to get regular CL income and will be big spenders. Perhaps not as big as their Madrid rivals or Barcelona, but they can comfortably outspend all the other clubs. As seasons go by, and more money is invested, expectations will naturally shift. If he does not find a way of playing better football, I think the fans will eventually get on his back.
No-one wants to see their team play defensive football for a long time. And this rings especially true when you've spent a lot of money on attacking players already, only for a large quantity of them to not succeed.